How do low carb diets affect the risk of diabetes

Do low-carb and/or ketogenic diets help with diabetes?

There is an ocean of information on weight loss, and in another article I explore the reliability and honesty of weight loss diet research and particularly opinion pieces. You might want to consider reading it gain an understanding potential pitfalls on only reading opinion pieces on this subject.

There is a fair amount of controversy over whether low carb (Atkins) diets reduce or increase the risk of diabetes.

Do low carb high protein diets reduce or increase the risk of diabetes?

Proponents of low carb diets claim that they lower blood glucose levels and therefore reduce the insulin spikes. Because high glucose levels are actually toxic to the body we normally respond with a spike in insulin, which communicates that glucose needs to be brought into the cells, where it is then burned or stored. Diabetic people are insulin resistant, meaning that the body does not bring enough blood glucose into the cells.

The argument goes that if there isn’t much of a blood glucose spike to begin with then the problem is circumnavigated.

Opponents of this view feel that the research tends to be too short term. They also point out that high protein diets might well increase the long term risk of diabetes.

Let’s take a look at the research itself!

A meta-analysis in support of the Mediterranean diet for reducing diabetes risk

Ajala et al., (2013) conducted a meta-analysis of the literature comparing low-carbohydrate, vegetarian, vegan, low–glycemic index (GI), high-fiber, Mediterranean, and high-protein diets with control diets including low-fat, high-GI and low-protein diets, in the management of diabetes. The low-carbohydrate, low-GI, Mediterranean, and high-protein diets all led to a greater improvement in glycemic control (thus lowering the risk of diabetes) with the Mediterranean diet significantly outperforming the rest.

Research indicating that ketogenic diets may help with diabetes

Yancy et al. considered this issue by using a Ketogenic diet in a study of 28 overweight subjects with Type 2 diabetes. The low-carb ketogenic diet significantly aided the diabetics to the extent that ‘diabetes medications were discontinued or reduced in most participants.’ Yancy et al. concluded from a study that ‘A high-starch, high-carbohydrate diet excessively stimulates appetite and disturbs energy balance in patients with the metabolic syndrome and type 2 diabetes. A reduction of carbohydrates normalises the balance, reduces insulin concentrations and favours utilization of stored fat as fuel as well as significantly reducing insulin resistance’.

Obviously this study does not examine a causal link between a high-carb diet and diabetes. It also does not examine the long term effects of this diet on diabetes. It does also need to be noted that only around 10% of diets claiming to be ‘ketogenic’ actually result in ketosis.

However, this study does conclude that low-carb, ketogenic diets can sometimes at least be a partial remedy for type 2 diabetes in the short term.

Research demonstrating that low carb diets help with diabetes

Nielsen et al., (2006) conducted a longitudinal study comparing a sample of type 2 diabetics consuming either a conventional high-carb diet or low-carb diet. The low-carb group was found to have significantly better weight loss and glycemic control over the first 6 months. The low carbohydrate group ‘mostly’ maintained glycemic control over the 22 month period.

Samaha et al., (2003) compared the efficacy of low-carb and low-fat diets on a sample of 132 obese subjects. Between-group and overall differences were small but significant, and the authors called for cautious interpretation. Nevertheless, they did conclude that ‘Severely obese subjects with a high prevalence of diabetes or the metabolic syndrome (demonstrated a) relative improvement in insulin sensitivity and triglyceride level’.

A meta-analysis in support of low carb diets for reducing diabetes risk

Santos et al., 2012 (Obesity Reviews) conducted a meta-analysis to examine the effects of low-carbohydrate diets on weight loss and cardiovascular problems. A total of 23 reports, corresponding to 17 clinical investigations, were identified as meeting the pre-specified criteria.

Long term versus short-term research studies

One would look at all these low-carb studies and feel pretty positive about the association between low carb diets and lowered risk of diabetes. It does need to be noted though that most of them are relatively short-term.

In my article on how high protein diets may lead to higher levels of diabetes, cancer and all-cause mortality I unpack some recent studies on how high protein (and therefore low carbohydrate) diets may increase the risk of diabetes. These research studies demonstrate how high protein diets increase insulin levels, IGF-1 and branch chain amino acids and in the process activate the mTOR signalling pathway. This over-stimulation of this pathway has been shown to be linked to increased degenerative diseases including diabetes and reduced lifespan.

In the one human study higher protein consumption levels resulted in a 74% increase in all-cause mortality in persons between 45 and 65 years of age.

Conclusions

In my opinion there seems to be strong evidence that low carb diets may reduce the risk of diabetes in the short term. It is also my opinion that more research needs to be done on link between high protein (and therefore low carb) consumption and risk of diabetes / all-cause mortality.

However, in my opinion the current evidence on the effect that low carb high protein diets have on diabetes and all-cause mortality in the longer term is also pretty powerful, if somewhat preliminary.. It is also concerning that part of the mechanism through which high protein diets reduce lifespan has to do with increased insulin, activation of mTOR signalling and insulin resistance, all of which form a part of the diabetes process.

So although there might be short-term benefits of low carb high protein diets for diabetics the current long term picture looks a tad bleaker at present.

References

Levine ME, Suarez JA, Brandhorst S, et al. Low Protein Intake Is Associated with a Major Reduction in IGF-1, Cancer, and Overall Mortality in the 65 and Younger but Not Older Population. Cell Metabolism. Published online March 4 2014. http://dx.doi.org/10.1016/j.cmet.2014.02.006